1. Field of the Invention
This invention relates to a process for producing in an industrially simple manner 6-methyl-3-hepten-2-one and 6-methyl-2-heptanone analogues (e.g., 6-methyl-2-heptanone or 6,10-dimethyl-2-undecanone), which serve as materials for producing phyton or isophytol. (The term "phyton", as used herein, means 6,10,14-trimethylpentadecan-2-one, otherwise known as phytone.) This invention also relates to a process for producing phyton or isophytol from 6-methyl-3-hepten-2-one or the 6-methyl-2-heptanone analogue.
2. Description of the Related Art
As well known, phyton and isophytol are compounds useful as intermediates for producing biologically active substances such as vitamin E [see Yuki Gosei Kagaku Kyokaishi, 20, 824-836 (1962)] and can be produced by various processes. From the viewpoint of industrial application, a process is considered to be favored in which a ketone having 8 carbon atoms represented by the following Formula (I) ##STR3##
(the dotted line in the Formula means that one or two carbon-carbon double bond(s) can be present so long as the valence of carbon at the position indicated by such double bond(s) is satisfied) is used as an intermediate (hereinafter the ketone represented by Formula (I) is referred to as "C8 terpene ketone".
Here, in an instance, the whole process for producing phyton and isophytol where 6-methyl-5-hepten-2-one is used as the C8 terpene ketone will be shown by the following scheme. ##STR4##
Thus, in the process for producing phyton or isophytol from the C8 terpene ketone, it basically proceeds that the principal carbon chain of the C8 terpene ketone is several times made longer by five carbons corresponding to the isoprene unit, followed by hydrogenation of the carbon-carbon double bond in the resulting compound. This basic procedure is not different whether or not unsaturated bonds are present, and at whatever positions they are, in the C8 terpene ketone. Accordingly, in the process for producing phyton or isophytol from C8 terpene ketone, how to produce the intermediate C8 terpene ketone with ease and at a low cost is one of important factors for the industrial application.
In this regard, as processes for producing the C8 terpene ketone, those shown below are known, for example.
Process (i): A process in which acetone, the starting material, is subjected to ethynylation by acetylene in the presence of an alkaline catalyst to form 3-methyl-1-butyn-3-ol and successive partial hydrogenation in the presence of a Lindlar catalyst, followed by reaction with diketene to form an ester derivative of acetoacetic acid. Thereafter, the ester thus formed is further subjected to Carroll rearrangement to produce 6-methyl-5-hepten-2-one [see, e.g., J. Org. Chem., 23, 153 (1958); Zh. Obshch. Chim., 28, 1444 (1958)].
Process (ii): A process in which isobutene, acetone and formaldehyde are allowed to react under conditions of a high temperature and a high pressure to give 6-methyl-6-hepten-2-one (see, e.g., German Patents No. 12 59 876 and No. 12 68 135 and U.S. Pat. No. 3,574,773).
Process (iii): A process in which prenyl chloride obtained by the reaction of isoprene with hydrogen chloride is allowed to react with acetone in the presence of an equimolar amount of an alkali based on the prenyl chloride to give 6-methyl-5-hepten-2-one (see, e.g., U.S. Pat. Nos. 3,983,175 and 3,984,475).
These processes for producing C8 terpene ketone, however, have problems as stated below.
The process (i) has a problem that it requires many steps resulting in a higher production cost. The process (ii) has a problem that it requires special manufacturing equipments because the reaction is carried out under conditions of a high temperature and a high pressure. In the process (iii), the use of an alkali in an equimolar amount based on the prenyl chloride results in the formation of a salt in a large quantity to make it necessary to take much labor for its disposal.
Accordingly, the present inventors have paid attention to 6-methyl-3-hepten-2-one as a compound that is different from the C8 terpene ketone and useful as a material for producing phyton or isophytol. This compound has an unsaturated bond at the .alpha.,.beta.-position to the carbonyl group, so it is difficult to make the principal carbon chain of the 6-methyl-3-hepten-2-one longer by five carbons corresponding to the isoprene unit at a high conversion. However, when it is subjected to hydrogenation reaction, it can be converted into 6-methyl-2-heptanone, a kind of the C8 terpene ketone, a material for producing phyton and isophytol.
As processes for producing 6-methyl-3-hepten-2-one, processes comprising subjecting isovaleraldehyde and acetone to aldol condensation in the presence of an aqueous alkali as a basic catalyst are known. Such processes are known to include the following.
Process (iv): A process in which an equimolar mixture of isovaleraldehyde and acetone is stirred at 20 to 25.degree. C. in the presence of an aqueous sodium hydroxide [see Nippon Kagaku Kaishi, 59, 224 (1938)].
process (v): A process in which isovaleraldehyde is added in a mixture of acetone, diethyl ether and an aqueous sodium hydroxide while keeping the reaction temperature at 15.degree. C. or below; the acetone being in an amount of 4 moles per mole of the isovaleraldehyde [see Bull. Soc. Chim. Fr., 112 (1957)].
In addition to the above, the following processes (vi) to (ix) are also known as processes for producing 6-methyl-3-hepten-2-one.
Process (vi): A process in which isovaleraldehyde and acetone are heated in the absence of a catalyst under pressure or in a sealed vessel to carry out reaction at a high temperature (300.degree. C.) and a high pressure (270 kg/cm.sup.2) (See British Patent No. 1,246,698).
Process (vii): A process in which isovaleraldehyde and acetone are allowed to react in the presence of zinc oxide at 180.degree. C. under 35 atmospheric pressure (see U.S. Pat. No. 4,005,147).
Process (viii): A process in which isoamyl alcohol and acetone are condensed in the presence of an aluminum isopropoxide [see Nippon Kagaku Kaishi, Vol. 81, p.675 (1960)].
Process (ix): A process in which acetylacetylene and triisobutylborane are allowed to react in the presence of oxygen [see J. Am. Chem. Soc., 92, 3503 (1970)].
However, the processes (vi) and (vii) both are carried out under conditions of a high temperature and a high pressure, so they require special manufacturing equipment. Moreover, the conversion of isovaleraldehyde is as low as 24% and 73%, respectively, which is not satisfactory. The process (viii) must use expensive aluminum isopropoxide in an equimolar amount based on the isoamyl alcohol, and the process (ix) must use very expensive acetylacetylene and triisobutylborane. Thus, the processes (vi) to (ix) can not be estimated industrially advantageous in view of manufacturing equipment and cost of materials.
In contrast, the processes comprising subjecting isovaleraldehyde and acetone to aldol condensation in the presence of an aqueous alkali have an advantage that the reaction can be carried out under mild conditions, using inexpensive materials. The process (iv), however, can give 6-methyl-3-hepten-2-one, the aldol condensate, only in a 35 to 40% yield at most. Also, the process (v) mainly forms 6-methyl-4-hydroxyheptan-2-one, and requires successive dehydration reaction in order to obtain the yield of the 6-methyl-3-hepten-2-one. In addition, the yield of the 6-methyl-3-hepten-2-one thus obtained is 51%, which is not satisfactory. Moreover, the process (v) must use acetone in excess, so it is not industrially advantageous in view of the necessity for recovering the excessive acetone and the volumetric efficiency of reaction.
The 6-methyl-2-heptanone formed by hydrogenation of 6-methyl-3-hepten-2-one is not only useful as a material for producing phyton and isophytol as previously stated, which are intermediates for producing vitamin E, but also useful as a material for producing perfumes such as tetrahydrolinalool and dihydrogeraniol [see, e.g., Bull. Soc. Chim. Fr., 1586 (1955)].
As conventional processes for producing 6-methyl-2-heptanone, processes (x) to (xv) shown below are known.
Process(x): A process in which an isoamyl halide and an acetoacetic acid ester are subjected to condensation reaction under alkaline conditions, followed by hydrolysis and then decarboxylation (see, e.g., Wagner, "SYNTHETIC ORGANIC CHEMISTRY", p.327, John Wiley & Sons, Inc.).
Process (xi): A process in which 6-methyl-5-hepten-2-one or 6-methyl-3,5-heptadien-2-one is subjected to hydrogenation in the presence of a hydrogenation catalyst such as Pd or Ni [see, e.g., European Patent No. 34,804; J. Org. Chem., 42, 1709 (1977); Izv. Akad. Nauk. SSSR. Khim., 10, 2381 (1972)].
Process (xii): A process in which 6-methyl-2-heptanol is oxidized [see, e.g., Recl. Trav. Chim. Pays-Bas, 28, 116 (1909)].
Process (xiii): A process in which 6-methyl-5-hepten-2-ol is treated with a mixture of 85% phosphoric acid and phosphorus pentoxide [see, Bull. Soc. Chim. Fr., 1799 (1963)].
Process (xiv) A process in which methyl vinyl ketone is subjected to 1,4-addition with an isobutyl magnesium halide [see, Bull. Chem. Soc. Jpn., 38, 29 (1965)].
Process (xv): A process in which isovaleraldehyde and acetone are allowed to react under a stream of hydrogen, in the presence of a catalyst comprised of a metal oxide and a metal belonging to Group VIII of the periodic table (See U.S. Pat. Nos. 4,146,581 and 4,212,825).
The above processes, however, have problems as discussed below.
In the process (x), a base is used in an equimolar amount based on the acetoacetic acid ester, so a salt is formed in a large quantity to require much labor for its disposal, resulting in a high cost for the production of the 6-methy-2-heptanone.
In the processes (xi) and (xii), the production of 6-methyl-5-hepten-2-one, 6-methyl-3,5-heptadien-2-one or 6-methyl-2-heptanol, the starting material, is complicated because many steps are required from inexpensive and readily available materials.
In the process (xiii), not only the production of the 6-methyl-5-hepten-2-ol is complicated because many steps are required from inexpensive and readily available materials, but also the 85% phosphoric acid and phosphorus pentoxide are used in a large quantity to require much labor for the disposal of waste water.
In the process (xiv), the isobutyl magnesium halide is used in an equimolar amount based on the methyl vinyl ketone, so a salt is formed in a large quantity to require much labor for its treatment, resulting in a high production cost. Moreover, methyl vinyl ketone, one of the materials, has so high a tendency to polymerization and also the other isobutyl magnesium halide is so sensitive to water and oxygen that they must be handled with care.
In the process (xv), the reaction is carried out under conditions of a high temperature and a high pressure, so it requires a special manufacturing equipment.
The above conventional processes for producing 6-methyl-2-heptanone have subjects to be settled in view of production cost and manufacturing equipment. Thus, no industrially advantageous process has been established for producing the 6-methyl-2-heptanone.
Besides the 6-methyl-2-heptanone, as intermediates for producing phyton or isophytol, one may contemplate making use of 6-methyl-2-heptanone analogues having 6-methyl-2-heptanon-7-yl residual groups, such as 6,10-dimethyl-2-decanone and 6,10,14-trimethyl-5,9-pentadecadien-2-one. Production processes for these, however, also is considered to have similar problems.